The present invention relates to methods and apparatuses for facsimile printing on paper sheets of constant and predetermined format. More particularly, the invention relates to printing methods comprising the steps of storing the pixels of all scanned lines of each page in turn for each transmitted document page, determining the number of lines of predetermined spacing to be reproduced and printing the page pixel by pixel, one line after another.
A particular important application of the invention lies with facsimile machines that print using an electro-photographic technique on precut sheets at a standardized format (generally A4 size in Europe).
Due to printing requirements, it is not possible to use the entire surface area of the sheet. The usable portion is limited by the need to reserve a few milimeters at the bottom of the sheet for taking hold of the sheet. When printing is performed by an electro-photographic technique, it is not possible to deposit ink or toner on the side margins of the paper. Finally, provision is generally made to print a call identification line or CIL consisting of alphanumeric characters at the top of the sheet. In general, the available area of an A4 size sheet (i.e. 210 mm.times.297 mm) is only 208 mm.times.289 mm.
In addition, the document as sent may have a format that is larger than the sheet format used for reproduction: in particular, its format may be B4 or the American foolscap of length 330 mm.
In the design of present facsimile machines, either the problem has been ignored, in which case information is lost if blank edges are not reserved in the document sent, or else attempts have been made to provide solutions that are not fully satisfactory.
One of the solutions that is already in use to take into account the impossibility of using the full length of a sheet may be called "line skip" or "nibbling" and is described in particular in documents WO-A-9108639 and WO-A-4885641 to which reference may be made. It consists in shortening the length to be printed by omitting lines of pixels at regular intervals. This technique reduces readability, and in particular can make some letters indistinguishable. It changes the shapes of figures: for example, a circle becomes an oval.